Knew my dog was going to pass

About a month ago I felt like there was something going on with my dog. I had no reason it was just a gut feeling maybe. I started talking with my kids and telling them she is getting older and a general talk about how one day we will probably have to make the choice to put her down, and I told my husband something was wrong. There were no obvious signs. Yesterday she became very sick very fast and we had to have her euthanized. It was very sudden and very fast but I'm lost. She was my best friend and I failed her. Did I sense this. Why did I not listen to my gut. She had a problem that was developing over a month or 2 maybe longer but had no idea! I look back now and see there were very small physical signs I missed but I felt it and missed the physical. Im so upset with myself.